Revert "Remove unneeded NestedConfigurationProperty"

This reverts commit 8048e2d6c2.

spring-boot-project/spring-boot-docs/src/docs/asciidoc/native-image/advanced-topics.adoc

@@ -6,10 +6,12 @@
 [[native-image.advanced.nested-configuration-properties]]
 === Nested Configuration Properties
 Reflection hints are automatically created for configuration properties by the Spring ahead-of-time engine.
+Nested configuration properties, however, *must* be annotated with `@NestedConfigurationProperty`, otherwise they won't be detected and will not be bindable.
 
 include::code:MyProperties[]
 
 The example above produces configuration properties for `my.properties.name` and `my.properties.nested.number`.
+Without the `@NestedConfigurationProperty` annotation on the `nested` field, the `my.properties.nested.number` property would not be bindable in a native image.
 
 NOTE: Please use public getters and setters, otherwise the properties will not be bindable.
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/nativeimage/advanced/nestedconfigurationproperties/MyProperties.java

@@ -17,12 +17,14 @@
 package org.springframework.boot.docs.nativeimage.advanced.nestedconfigurationproperties;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.context.properties.NestedConfigurationProperty;
 
 @ConfigurationProperties(prefix = "my.properties")
 public class MyProperties {
 
 	private String name;
 
+	@NestedConfigurationProperty
 	private Nested nested = new Nested();
 
 	// @fold:on // getters / setters...